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Abstract: Based on coronary angiography and interoperative inspection, anomalous origin of coronary artery crossing the right ventricular outflow tract (RVOT) is common in tetralogy of Fallot (TOF) patients. However, other coronary anomalies may be underestimated due to the overlying myocardium, epicardial fat, or adhesions due to previous palliative surgery. Currently, coronary artery visibility dramatically improved by multislice computed tomography (MSCT). We performed this study to assess the coronary arteries anatomy in TOF patients using MSCT.All TOF patients underwent MSCT examination at our centre from 2013 till 2019 were included. Assessment of the coronary arteries' origin and course were performed. Presence of myocardial bridge were assessed, and indexed RV mass was calculated.318 TOF patients were included, median age 2 years (range 1 month-46 years), 175 males (55%). The abnormal coronary artery origin and course were detected in 20 patients (6%); coronary artery crossed RVOT in 13 patients (65%), 5 patients (25%) had a retro-aortic course and 2 patient (10%) had inter-arterial course. Myocardial bridges of left anterior descending artery or/and right coronary artery were reported in 100 patients (36%), no myocardial bridge of left circumflex was reported. RV mass was 29.0 ± 21.1 g/m2. There was no correlation between RV mass and presence of myocardial bridges.MSCT is a useful imaging modality for detection of coronary arteries anomalies in TOF patients. Coronary artery crossing RVOT is not the only abnormal course and myocardial bridging is not a rare finding. Further studies are needed to demonstrate the clinical significance of these observations., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: CAD-RADS was developed to standardize communication of per-patient maximal stenosis on coronary CT angiography (CCTA) and provide treatment recommendations and may impact primary prevention care and resource utilization. The authors sought to evaluate CAD-RADS adoption on preventive medical therapy and risk factor control amongst a mixed provider population., Methods: Statins, aspirin (ASA), systolic blood pressure and, when available, lipid panel changes were abstracted for 1796 total patients undergoing CCTA in the 12 months before (non-standard reporting, NSR, cohort) and after adoption of the CAD-RADS reporting template. Only initiation of a medication in a treatment naïve patient, escalation from baseline dose, or transition to a higher potency was considered an escalation/initiation in lipid therapy., Results: The CAD-RADS reporting template was utilized in 83.7% (751/897) of CCTAs after the CAD-RADS adoption period. After adjusting for any coronary artery disease (CAD) on CCTA, statin initiation/escalation was more commonly observed in the CAD-RADS cohort (aOR 1.46; 95%CI 1.12-1.90, p = 0.005), driven by higher rates of new statin initiation (aOR 1.79; 95%CI 1.23-2.58, p = 0.002). This resulted in a higher observed rates of total cholesterol improvement in the CAD-RADS cohort (58% vs 49%, p = 0.016). New ASA initiation was similar between reporting templates after adjustment for CAD on CCTA (aOR 1.40; 95%CI 0.97-2.02, p = 0.069). The ordering provider's specialty (cardiology vs non-cardiology) did not significantly impact the observed differences in initiation/escalation of statins and ASA (pinteraction = NS)., Conclusions: Adoption of CAD-RADS reporting was associated with increased utilization of preventive medications, regardless of ordering provider specialty., (Copyright © 2020 Society of Cardiovascular Computed Tomography. All rights reserved.)

Background/aim: In local staging of gastric adenocarcinoma CT is the modality of choice. Less frequently used in a few selected patients is echo-endoscopy. Aim of this study was to evaluate the accuracy of hydro-multidetector-computed tomography (hydro-MDCT) in the evaluation of gastric adenocarcinomas with subsequent surgical and histopathological correlation to select cases for echo-endoscopy., Patients and Methods: A total of 65 patients with gastric adenocarcinomas, diagnosed by endoscopy and biopsy, underwent contrast-enhanced hydro-MDCT with subsequent tumor, nodes, metastases (TNM) classification. The distension of the gastric lumen was obtained after the oral administration of 500 ml of water., Results: Hydro-MDCT always detected gastric cancer and in 49/65 patients the assessment of T-parameter was identical to the histopathological results (accuracy: 75%). We found overstaging in 12 and understaging in 4 cases. N-parameter with MDCT was in agreement with histo-pathology in 69%of patients; in metastatic disease hydro-MDCT had an accuracy of 99%. Hydro-MDCT has proven to be a reliable diagnostic technique in evaluating gastric cancer T3-T4 stages in comparison to T1 and T2: in defining T2-stage we found the highest number of errors (37%)., Conclusion: Hydro-MDCT is a reliable technique in the preoperative staging of gastric adenocarcinoma. Echo-endoscopy could be particularly useful in doubtful cases to evaluate the muscularis propria infiltration (T2 vs. T3) and characterize the peri-gastric lymph nodes., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Paleopathology and anthropology are fields of research which have benefited from the use of diagnostic imaging since its introduction in the clinical setting. The deriving discipline, that is, paleoimaging, has effectively employed several diagnostic techniques. However, while Multi-Slice Computed Tomography (MSCT) has found its role in paleoimaging, Cone-Beam Computed Tomography (CBCT), despite its several advantages with regard to MSCT, is still struggling to find a clear position in this field. The aim of our study is to evaluate the possible advantages CBCT could bring to paleoimaging. We describe the characteristics and role of CBCT in clinical applications, in forensic and legal medicine, and in paleopathology. We report the study of an ancient mandible by means of CBCT and MSCT, in order to compare the quality of the images in terms of spatial resolution. CBCT allows to obtain good quality images of mineralized tissues. Moreover, the possibility of imaging metallic manufacts makes the technique suitable for the study not only of bony remains, but also of museum and archaeological artifacts. Our study highlights the strengths of CBCT as a valid imaging technique for the study of ancient bone remains and manufacts. A revision of the current uses of CBCT is provided and gives insights into the possible role it can cover in bioarchaeological studies. Further evaluation is needed in terms of possible applications of this technique to paleopathology. We strongly encourage the use of CBCT in paleoimaging, and suggest a broader application of the technique to the study of archaeological samples.

Objective: To compare left atrial volume (LAV) and right atrial volume (RAV) determined by 2-D and 3-D echocardiographic methods with the LAV and RAV determined by ECG-gated multidetector CT (MDCT) for healthy dogs., Animals: 11 healthy purpose-bred young adult hound-type dogs., Procedures: Each dog was anesthetized and underwent MDCT and a complete echocardiographic examination. Modality-specific software was used to measure the respective atrial volumes at ventricular end systole, and LAV and RAV measurements were subsequently indexed to body weight and compared among imaging modalities., Results: The LAV determined by echocardiographic methods did not differ significantly from the LAV determined by MDCT. However, the RAV determined by 3-D echocardiography and 2-D echocardiography via the left apical and left cranial windows differed significantly from the RAV determined by MDCT. Bland-Altman analyses indicated that the indexed LAV and RAV determined by echocardiographic methods were systematically underestimated, compared with MDCT measurements, but the bias was much smaller for LAV than for RAV., Conclusions and Clinical Relevance: Results suggested that, for dogs, echocardiography might be an acceptable alternative to MDCT for measurement of LAV but not for measurement of RAV. However, the study population was small and homogenous in terms of breed, age, and weight. These findings need to be validated in a larger, more varied population of dogs with and without cardiac disease.

Purpose: A newly developed image processing technique fuses conventional windows into a single 'All-In-One' (AIO) window. This study aims to evaluate variability of CT measurement of lesions in thoracic oncology patients on this novel AIO-window., Methods: Six radiologists with different levels of expertise measured 368 lesions of various size, origin and sharpness. All lesions were measured twice on the AIO-window and twice on the conventional window settings. Intraclass correlation coefficients and Bland-Altman plots were used to assess intra- and interobserver variability., Results: Overall intra-observer agreement for lesion diameters on the AIO-window and conventional window settings was 0.986 (95% Confidence interval (CI): 0.983-0.989) and 0.991 (95% CI 0.989-0.993) respectively. For interobserver agreement this was 0.982 (95% CI 0.979-0.985) (AIO) and 0.979 (95% CI 0.957-0.982) (conventional). For both the AIO and conventional windows, intra- and interobserver agreement were dependent on size, sharpness and reader experience. Measurement variability decreased with increasing lesion size. Regarding sharpness, inter- and intra-observer agreement ranged from 0.986-0.989 (AIO) and 0.985-0.992 (conventional) for well-defined lesions and from 0.978-0.983 (AIO) and 0.974-0.991 (conventional) for ill-defined lesions., Conclusions: Lesion diameters were consistently smaller on the AIO-window compared to conventional window settings. Overall intra- and interobserver variability rates were similar for the AIO-window and conventional window settings. We conclude that the AIO-window offers a reliable and reproducible alternative for measurement of thoracic lesions.

Aim: To evaluate the effect of iso-osmolar contrast media (IOCM) at different tube voltages on image quality for abdominal computed tomography (CT) in paediatric patients., Materials and Methods: The low osmolar contrast media (LOCM) group and IOCM group consisted of 101 and 102 CT examinations, respectively, in patients <18 years old. Images were reviewed retrospectively. Objective measurement of the contrast enhancement and noise were analysed and contrast-to-noise ratios (CNRs) of the abdominal aorta, portal vein, and liver were calculated. Four radiologists participated in subjective analysis using a four-point scale system to evaluate degrees of contrast enhancement, image noise, beam-hardening artefact, and overall image quality. Reader performance for correctly differentiating the two kinds of contrast media was evaluated., Results: Regarding the objective measurement, contrast enhancement was significantly higher in the LOCM group (p<0.05). In subjective analysis, only CT using 120 kVp showed significantly stronger enhancement in the LOCM group (p=0.002), and sensitivity to differentiate the IOCM was 80.6%. Overall sensitivity and specificity for correctly differentiating IOCM were 57.1%, and 56.9%, respectively., Conclusion: The application of IOCM was found to be feasible for performing paediatric abdominopelvic CT with a low tube voltage protocol. Although objective measurements of contrast enhancement were significantly lower in the IOCM group, subjective contrast enhancement and image quality assessments were not statistically different between groups., (Copyright © 2019 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: To compare image quality and radiation doses for chest DECT acquired with dual-source and rapid-kV switching techniques., Materials and Methods: Our institutional Review Board approved retrospective study included 97 patients (54 men, 43 women; 63 ± 14 years) who underwent contrast-enhanced chest DECT with both single source, rapid kV-switching (SS-DECT) and dual source (DS-DECT) techniques per standard of care departmental protocols. Reconstructed images from both scanners had identical section thickness and section interval for virtual monoenergetic and material decomposition iodine (MDI) images. Two thoracic radiologists independently evaluated all DECT for findings, quality of images, perfusion defects (MDI), and presence of artifacts. Radiation dose descriptor, size-specific dose estimates (SSDE), was recorded. Data were analyzed with Wilcoxon Signed Rank and Cohen's Kappa tests., Results: There were no significant differences in patient weight or SSDE for the two DECT techniques (p > 0.06). Both radiologists reported no difference in lesion and artifact evaluation on the virtual monoenergetic images from either technique (p > 0.05). However, SS-DECT (in 63-71/97 patients) had substantial artifactual heterogeneity in pulmonary perfusion on MDI images compared to none on DS-DECT (p < 0.001)., Conclusion: Despite identical patients and associated radiation doses, there were substantial differences in material decomposition iodine images generated from SS-DECT and DS-DECT techniques. Pulmonary heterogeneity on MDI images from SS-DECT leads to artifactual areas of low perfusion and can confound interpretation of true pulmonary perfusion., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives: To evaluate the image quality of ultralow-dose computed tomography (ULDCT) reconstructed with knowledge-based iterative model reconstruction (IMR) in patients with pulmonary tuberculosis (TB)., Methods: This IRB-approved prospective study enrolled 59 consecutive patients (mean age, 43.9 ± 16.6 years; F:M 18:41) with known or suspected pulmonary TB. Patients underwent a low-dose CT (LDCT) using automatic tube current modulation followed by an ULDCT using fixed tube current. Raw image data were reconstructed with filtered-back projection (FBP), hybrid iterative reconstruction (iDose), and IMR. Objective measurements including CT attenuation, image noise, and contrast-to-noise ratio (CNR) were assessed and compared using repeated-measures analysis of variance. Overall image quality and visualization of normal and pathological findings were subjectively scored on a five-point scale. Radiation output and subjective scores were compared by the paired Student t test and Wilcoxon signed-rank test, respectively., Results: Compared with FBP and iDose, IMR yielded significantly lower noise and higher CNR values at both dose levels (p < 0.01). Subjective ratings for pathological findings including centrilobular nodules, consolidation, tree-in-bud, and cavity were significantly better with ULDCT IMR images than those with LDCT iDose images (p < 0.01), but blurred edges were observed. With IMR implementation, a 59% reduction of the mean effective dose was achieved with ULDCT (0.28 ± 0.02 mSv) compared with LDCT (0.69 ± 0.15 mSv) without impairing image quality (p < 0.001)., Conclusions: IMR offers considerable noise reduction and improvement in image quality for patients with pulmonary TB undergoing chest ULDCT at an effective dose of 0.28 mSv., Key Points: • Radiation dose is a major concern for tuberculosis patients requiring repeated follow-up CT. • IMR allows substantial radiation dose reduction in chest CT without compromising image quality. • ULDCT reconstructed with IMR allows accurate depiction of CT features of pulmonary tuberculosis.

Aim: To provide an overview on dose reduction and image quality after the installation of a third-generation dual-source CT (dsCT) in a Pediatric Radiology Department., Materials and Methods: We included pediatric patients (< 20 years old) undergoing CT for oncological staging (neck, chest and abdomen) or low-dose chest CT for lung diseases. Each of these two groups were further divided in two age groups (≤ or > 10 years old) including patients scanned in the same period of two consecutive years, in 2017 with a 16-row LightSpeed CT (GE Healthcare) or in 2018 with a Somatom Force dsCT (Siemens Healthineers). Technical parameters such as kVp, mAs, slice thickness, exposure times and dose indicators were retrieved and compared. Image quality was evaluated in consensus by two radiologists on a five-point semiquantitative scale. Nonparametric tests were used., Results: In oncological patients, significantly lower kVp and tube current with better image quality were achieved with the dsCT. Radiation dose (total DLP) was 5-6 times lower with dsCT, thanks also to virtual non-contrast images. In low-dose chest CT, the frequent use of tin filter required higher tube current; a total DLP 3 times lower was achieved with dsCT in patients ≤ 10 years old. The image quality was better with the dsCT in low-dose chest CT protocols., Conclusion: The third-generation dsCT provides high-quality images with reduced motion artifacts at lower dose.

Objectives: To evaluate machine learning (ML) to detect chest CT examinations with dose optimization potential for quality assurance in a retrospective, cross-sectional study., Methods: Three thousand one hundred ninety-nine CT chest examinations were used for training and testing of the feed-forward, single hidden layer neural network (January 2016-December 2017, 60% male, 62 ± 15 years, 80/20 split). The model was optimized and trained to predict the volumetric computed tomography dose index (CTDI vol ) based on scan patient metrics (scanner, study description, protocol, patient age, sex, and water-equivalent diameter (D W )). The root mean-squared error (RMSE) was calculated as performance measurement. One hundred separate, consecutive chest CTs were used for validation (January 2018, 60% male, 63 ± 16 years), independently reviewed by two blinded radiologists with regard to dose optimization, and used to define an optimal cutoff for the model., Results: RMSE was 1.71, 1.45, and 1.52 for the training, test, and validation dataset, respectively. The scanner and D W were the most important features. The radiologists found dose optimization potential in 7/100 of the validation cases. A percentage deviation of 18.3% between predicted and actual CTDI vol was found to be the optimal cutoff: 8/100 cases were flagged as suboptimal by the model (range 18.3-53.2%). All of the cases found by the radiologists were identified. One examination was flagged only by the model., Conclusions: ML can comprehensively detect CT examinations with dose optimization potential. It may be a helpful tool to simplify CT quality assurance. CT scanner and D W were most important. Final human review remains necessary. A threshold of 18.3% between the predicted and actual CTDI vol seems adequate for CT quality assurance., Key Points: • Machine learning can be integrated into CT quality assurance to improve retrospective analysis of CT dose data. • Machine learning may help to comprehensively detect dose optimization potential in chest CT, but an individual review of the results by an experienced radiologist or radiation physicist is required to exclude false-positive findings.

Objectives: To assess the ability of multislice detector computed tomography (MDCT) to differentiate old versus acute/subacute vertebral fractures (VF) and to identify characteristic MDCT imaging signs., Methods: 74 consecutive patients demonstrated 192 VF that were classified as either acute/subacute or old based on magnetic resonance imaging, MDCT, and clinical information as reference standard. Classification as acute/subacute versus old fractures based on MDCT alone was evaluated on a Likert scale by 2 independent radiologists. Morphologic MDCT features of fractures, such as trabecular compaction or fracture line, were recorded. Receiver operating characteristic analyses and Cohen's κ were used to assess the discriminatory power of the MDCT and interrater agreement, respectively., Results: Out of all 192 VF, 148 fractures were acute/subacute and 44 were old according to the reference standard. Receiver operating characteristic analyses of sole MDCT assessment showed very good identification of acute/subacute VF, with areas under the curve of 0.854 and 0.861 for readers 1 and 2, respectively. When indeterminate findings were treated as acute/subacute fractures, sensitivity and specificity were 97.2% and 58.1% for reader 1 and 94.5% and 65.1% for reader 2. Interrater agreement regarding fracture age was good (weighted Cohen's κ = 0.607). Trabecular compression/callus distinct from the cortex (double compaction sign) was present in approximately half of acute/subacute VF and highly specific for acute/subacute VF (specificity = 93.2% and 88.6% for readers 1 and 2, respectively)., Conclusion: The acuity of VF can be assessed by MDCT alone with high sensitivity and in case of a double compaction sign with high specificity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Multidetector computed tomography (MDCT) images for rhinosinusitis may have a risk of radiation hazards. Reduction in radiation dose may lead to a compromise in quality of MDCT images and have chances of postoperative complications., Objective: The aim of the study was to test the applicability of low-dose MDCT protocols for decision-making of sinus surgeries of patients with uncontrolled chronic rhinosinusitis., Design: Randomized, double-blind (patients and evaluators blind), controlled, trial., Setting: People's Hospital of Guanghan, China., Patients: A total of 288 patients with clinically confirmed uncontrolled chronic rhinosinusitis were subjected to randomization (1:1 ratio)., Interventions: Patients were subjected to low-dose preoperative protocols of MDCT (n = 144; ldMDCT group) or standard-dose preoperative protocols of MDCT (n = 144; sdMDCT group)., Outcome Measures: Image analysis was performed by the workstation. Lund-Mackay score, modified Lund-Mackay score, estimated radiation exposure, and surgical complications were evaluated for each patient. The χ independent test or 2-tailed paired t test were performed for statistical analysis., Results: The preoperative MDCT images for standard-dose protocol had better quality than low-dose protocol (P < .001, q = 4.57). The area of images that give confidence for sinus surgery at one time was higher for standard-dose MDCT protocol technique than low-dose MDCT protocol method. Patients of ldMDCT group with large growth of nasal polyps (P = .03, q = 5.35) and complete opacification of sinuses (P = .03, q = 7.94) had complications after sinus surgeries. Either low-dose or standard-dose MDCT protocol was performed, the experience of otolaryngologist had decreased complication after surgeries., Conclusion: Preoperative low-dose MDCT should be used for diagnosis of uncontrolled chronic rhinosinusitis for decision making of sinus surgeries., Level of Evidence: III., Trial Registration: researchregistry4264 dated 1 March 2016 (www.researchregistry.com).

Objective:: To determine the diagnostic performance of CT in the assessment of mild hepatic steatosis by comparison with MR mDIXON-Quant as a reference standard, and to explore their clinical applications., Methods:: In this prospective study 169 volunteers were included. Each subject underwent CT and MR mDIXON-Quant examinations. Hepatic steatosis evaluations were performed via liver attenuation alone (CT L), liver to spleen attenuation ratio (CT L/S), difference between liver and spleen attenuation (CT L-S), and MR mDIXON-Quant imaging. The effectiveness of CT L, CT L/S, and CT L-S in diagnosing hepatic steatosis severity of ≥5%, ≥10%, and ≥15% was compared, using mDIXON-Quant results as standard., Results:: 65 subjects exhibited mild hepatic steatosis. Hepatic steatosis measurement with mDIXON-Quant was strongly correlated with the three CT methods. Using cutoff value, the sensitivity and specificity of diagnosing hepatic steatosis ≥5, ≥10, and ≥15% were 64.6, 91.3, 100%, and 90.4, 89.7, 93.0% for CT L; 50.8, 87.0, 100%, and 96.2, 98.6, 97.5% for CT L/S; and 67.7, 87.0, 100%, and 81.7, 98.6, 97.5% for CT L-S, respectively. ROC analysis indicated that 58.9, 56.5, and 52.8 HU for CT L; 1.06, 0.98, and 0.90 HU for CT L/S; and 6.21,-1.04, and -4.93 HU for CT L-S were cutoff values for diagnosing hepatic steatosis ≥5%,≥10%, and ≥15%, respectively., Conclusions:: The three CT methods exhibit better agreements with mDIXON-Quant imaging for diagnosing hepatic steatosis ≥10%. Hence, CT and mDIXON-Quant could serve as suitable tools for the accurate quantification of mild hepatic steatosis., Significant Finds of the Study:: The close agreement between the three different CT methods (based on our cutoff values) and mDIXON-Quant imaging suggests that CT could accurately diagnose hepatic steatosis ≥10%. Thus, CT and mDIXON-Quant imaging can accurately measure mild hepatic steatosis., What This Study Adds:: Only few studies have compared hepatic steatosis quantification between CT and mDIXON-Quant. We are the first to determine the diagnostic performance of unenhanced CT for quantitatively assessing mild hepatic steatosis, in reference to magnetic resonance mDIXON-Quant imaging.

Computed tomography (CT) has become an important modality in the evaluation of coronary artery disease (CAD). The tremendous technological advances in CT in the last two decades has made it possible to obtain high quality images of coronary arteries with high spatial and temporal resolutions. Multiple trials have confirmed the accuracy of CT compared to invasive catheter angiography. CT is also able to evaluate beyond the lumen in characterizing and quantifying atherosclerotic plaques, including evaluation of high risk features. Although CTA has low specificity in identification of lesion-specific ischemia, functional techniques are now possible such as CT myocardial perfusion and CT-fractional flow reserve (FFR) which evaluate the hemodynamic significance of stenosis and help with revascularization strategies. Multi-energy CT provides additional information beyond what is possible with a conventional CT and is useful in variety of clinical applications, including myocardial perfusion imaging, lesion characterization and low contrast studies. Large trials have confirmed the ability of CT to predict major adverse cardiovascular events and recent trials have even demonstrated improved clinical outcomes by using CT for the evaluation of CAD. CT is also useful in structural heart disease and 3 D printing is now increasingly used for surgical/interventional planning. Machine learning is evolving rapidly and is likely to impact diagnosis and management.

Rationale and Objectives: This study aims to determine the optimal photon energy for image quality of the pulmonary arteries (PAs) on dual-energy computed tomography (CT) pulmonary angiography (CTPA) utilizing low volumes of iodinated contrast., Materials and Methods: The study received institutional review board exemption and was Health Insurance Portability and Accountability Act compliant. Adults (n = 56) who underwent dual-energy CTPA with 50-60 cc of iodinated contrast on a third-generation dual-source multidetector CT were retrospectively and consecutively identified. Twelve virtual monoenergetic kiloelectron volt (keV) image data sets (40-150 keV, 10-keV increments) were generated with a second-generation noise-reducing algorithm. Standard regions of interest were placed on main, right, left, and right interlobar pulmonary arteries; pectoralis muscle; and extrathoracic air. Attenuation [mean CT number (Hounsfield unit, HU)], noise [standard deviation (HU)], signal to noise (SNR), and contrast to noise ratio were evaluated. Three blinded chest radiologists rated (from 1 to 5, with 5 being the best) randomized monoenergetic and weighted-average images for attenuation and noise. P <.05 was considered significant., Results: Region of interest mean CT number increased as keV decreased, with 40 keV having the highest value (P < .001). Mean SNR was highest for 40-60 keV (P <.05) (14.5-14.7) and was higher (P <.05) than all remaining energies (90-150 keV) for all vessel regions combined. Contrast to noise ratio was highest for 40 keV (P <.001) and decreased as keV increased. SNR was highest at 60 and 70 keV, only slightly higher than 40-50 keV (P <.05). Reader scores for 40-50 keV were greater than other energies and weighted-average images (P <.05)., Conclusions: Kiloelectron volt images of 40-50 keV from the second-generation algorithm optimize attenuation on dual-energy CTPA and can potentially aid in interpretation and avoiding nondiagnostic examinations., (Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Background: The extent of aortic valve calcification is an important determinant of procedural success in transcatheter aortic valve implantation (TAVI). We sought to validate device landing zone calcium volume (DLZ-CV) measurements on contrast-enhanced multidetector computed tomography (MDCT) with non-contrast-enhanced scans as reference., Methods: We determined DLZ-CV in 141 patients undergoing transfemoral TAVI. Non-contrast-enhanced images were analyzed using a threshold of 130 HU as reference (DLZ-CV 130 ). For contrast-enhanced scans, we applied various thresholds including 450 HU (DLZ-CV 450 ), 850 HU (DLZ-CV 850 ), mean aortic attenuation (Atten Ao ) + 2 SD (DLZ-CV 2SD ), Atten Ao  + 4 SD (DLZ-CV 4SD ), Atten Ao  + 4 SD + 5 mm 3 volume filter (DLZ-CV 4SD+ ), and based on visual estimation (DLZ-CV vis ). We compared DLZ-CV values between patients with versus without paravalvular leak (PVL), and between patients with versus without post-dilatation stratified by the type of prosthesis., Results: All DLZ-CV measurements on contrast-enhanced scans significantly differed from DLZ-CV 130 (p < 0.001 for all comparisons). The best approximation to DLZ-CV 130 was achieved with DLZ-CV 4SD+ (508 mm 3 [332-772]; Pearson correlation: R = 0.87, p < 0.001; Bland-Altman: mean difference 1339 mm 3 [limits of agreement 79;2600]). Moreover, DLZ-CV 4SD+ allowed for discrimination of PVL ≥1° or the need for post-dilatation in patients receiving self-expanding prostheses. Procedural outcome using balloon-expandable prostheses was independent of DLZ-CV., Conclusion: Measurement of DLZ-CV using contrast-enhanced scans with unadjusted thresholds results in incorrect estimation of the calcium volume. The use of a scan-specific individual HU threshold including a volume filter (DLZ-CV 4SD+ ) provides the best approximation to the reference and allows for discrimination of PVL ≥ 1° in patients receiving the Acurate neo prosthesis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

There is an urgent need to develop new protocols to reduce radiation dose of coronary computed tomography angiography (CTA). The aim of this pilot study was to demonstrate the feasibility of an ultra-low dose CTA scanning., (Copyright © 2017. Published by Elsevier B.V.)

Aims: To determine the diagnostic accuracy of semi-automatic quantitative metrics compared to expert reading for interpretation of computed tomography perfusion (CTP) imaging., Methods: The CORE320 multicenter diagnostic accuracy clinical study enrolled patients between 45 and 85 years of age who were clinically referred for invasive coronary angiography (ICA). Computed tomography angiography (CTA), CTP, single photon emission computed tomography (SPECT), and ICA images were interpreted manually in blinded core laboratories by two experienced readers. Additionally, eight quantitative CTP metrics as continuous values were computed semi-automatically from myocardial and blood attenuation and were combined using logistic regression to derive a final quantitative CTP metric score. For the reference standard, hemodynamically significant coronary artery disease (CAD) was defined as a quantitative ICA stenosis of 50% or greater and a corresponding perfusion defect by SPECT. Diagnostic accuracy was determined by area under the receiver operating characteristic curve (AUC)., Results: Of the total 377 included patients, 66% were male, median age was 62 (IQR: 56, 68) years, and 27% had prior myocardial infarction. In patient based analysis, the AUC (95% CI) for combined CTA-CTP expert reading and combined CTA-CTP semi-automatic quantitative metrics was 0.87(0.84-0.91) and 0.86 (0.83-0.9), respectively. In vessel based analyses the AUC's were 0.85 (0.82-0.88) and 0.84 (0.81-0.87), respectively. No significant difference in AUC was found between combined CTA-CTP expert reading and CTA-CTP semi-automatic quantitative metrics in patient based or vessel based analyses(p > 0.05 for all)., Conclusion: Combined CTA-CTP semi-automatic quantitative metrics is as accurate as CTA-CTP expert reading to detect hemodynamically significant CAD., (Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Purpose To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). Materials and Methods All patients gave written informed consent prior to inclusion in this institutional review board-approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. Results The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P < .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P < .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). Conclusion This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. © RSNA, 2017 Online supplemental material is available for this article.

Objective: Staging laparoscopy (SL) is the gold standard investigation for detecting peritoneal metastases (PM) in patients with esophagogastric cancer but computed tomography (CT) has undergone significant improvements in recent years. The aim of this study was to investigate whether CT can replace SL in the detection of PM., Materials and Methods: Patients undergoing SL between January 2008 and December 2009 were identified from a prospectively collected database, operation notes were reviewed for the detection of PM. Corresponding CTs were reassessed by 2 experienced gastrointestinal radiologists, blinded to the SL results., Results: In total, 74 patients undergoing SL were included. Sensitivity and specificity of SL for PM were 94.1% (95% confidence interval, 69.2-99.7) and 100% (90.7-100). Sensitivity and specificity of CT were 58.8% (33.5-80.6) and 89.6% (76.6-96.1), respectively. Area under the curve of receiver operating characteristic curves for SL and CT were 0.971 (SE, 0.033) and 0.742 (SE, 0.78), respectively., Conclusions: CT cannot replace SL for the detection of PM in lower esophageal and gastric cancer.

Background: Multidetector computed tomography (MDCT) exhibited wide ranges of sensitivities and specificities for lymph node assessment of gastric cancer (GC) in several individual studies. This present meta-analysis was carried out to evaluate the value of MDCT in diagnosis of preoperative lymph node metastasis (LNM) and to explore the impact factors that might explain the heterogeneity of its diagnostic accuracy in GC., Methods: A comprehensive search was conducted to collect all the relevant studies about the value of MDCT in assessing LNM of GC within the PubMed, Cochrane library and Embase databases up to Feb 2, 2016. Two investigators independently screened the studies, extracted data, and evaluated the quality of included studies. The sensitivity, specificity, and area under ROC curve (AUC) were pooled to estimate the overall accuracy of MDCT. Meta-regression and subgroup analysis were carried out to identify the possible factors influencing the heterogeneity of the accuracy., Results: A total of 27 studies with 6519 subjects were finally included. Overall, the pooled sensitivity, specificity, and AUC were 0.67 (95% CI: 0.56-0.77), 0.86 (95% CI: 0.81-0.90), and 0.86 (95% CI: 0.83-0.89), respectively. Meta-regression revealed that MDCT section thickness, proportion of serosal invasion, and publication year were the main significant impact factors in sensitivity, and MDCT section thickness, multiplanar reformation (MPR), and reference standard were the main significant impact factors in specificity. After the included studies were divided into 2 groups (Group A: studies with proportion of serosa-invasive GC subjects ≥50%; Group B: studies with proportion of serosa-invasive GC subjects <50%), the pooled sensitivity in Group A was significantly higher than in Group B (0.84 [95% CI: 0.75-0.90] vs 0.55 [95% CI: 0.41-0.68], P < .01). For early gastric cancer (EGC), the pooled sensitivity, specificity, and AUC were 0.34 (95% CI: 0.15-0.61), 0.91 (95% CI: 0.84-0.95), and 0.83 (95% CI: 0.80-0.86), respectively., Conclusion: To summarize, MDCT tends to be adequate to assess preoperative LNM in serosa-invasive GC, but insufficient for non-serosa-invasive GC (particularly for EGC) owing to its low sensitivity. Proportion of serosa-invasive GC subjects, MDCT section thickness, MPR, and reference standard are the main factors influencing its diagnostic accuracy.

Objectives: Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT)., Methods: We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard., Results: We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001)., Conclusions: Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions., Key Points: • Computed tomography angiography tends to overestimate stenosis in calcified coronary artery. • Dual-energy CT enables us to suppress calcification of coronary artery lesions. • Calcification-suppressed material density imaging reduces false-positive diagnosis of calcified lesion.

Purpose: To investigate the Liver Imaging Reporting and Data System (LI-RADS) v2014 categorization of hepatocellular carcinomas (HCCs) on gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) in comparison with multiphasic multidetector computed tomography (MDCT)., Materials and Methods: Our Institutional Review Board approved this retrospective study and waived the requirement for informed consent. We included 182 high-risk patients with 216 pathologically confirmed HCCs who underwent both Gd-EOB-MRI at 1.5 or 3T and multiphasic MDCT. Two independent radiologists assessed the presence or absence of major HCC features and assigned LI-RADS categories before and after considering ancillary features on both MRI and MDCT. Finally, sensitivities of LR-5/5v and frequencies of major HCC features were compared between MRI and MDCT using the McNemar test., Results: Sensitivities of LR-5/5v were not significantly different between MRI and MDCT (63.4% [137/216] vs. 64.4% [139/216], P = 0.831; 60.6% [131/216] vs. 60.6% [131/216], P = 0.868, for reviewers 1 and 2, respectively). Among major HCC features seen on consensus review, washout and capsule appearance were less frequently observed on MRI than on MDCT (69.0% [149/216] vs. 87.0% [188/216], P < 0.001 and 17.1% [37/216] vs. 31.5% [68/216], P < 0.001), while no significant differences were found for arterial hyperenhancement (88.9% [192/216] vs. 84.7% [183/216], P = 0.081). Ancillary features led to category changes in 18.1% (39/216) of nodules on MRI (all, LR-3 to LR-4), while no changes were seen on MDCT., Conclusion: Using LI-RADS, Gd-EOB-MRI showed comparable sensitivity to multiphasic MDCT for the diagnosis of HCCs, and ancillary features of MRI frequently led to the upgrade of nodules from LR-3 to LR-4., Level of Evidence: 3 J. Magn. Reson. Imaging 2017;45:731-740., (© 2016 International Society for Magnetic Resonance in Medicine.)

The national diagnostic reference level service (NDRLS), was launched in 2011, however no paediatric data were submitted during the first calendar year of operation. As such, Australian national diagnostic reference levels (DRLs), for paediatric multi detector computed tomography (MDCT), were established using data obtained from a Royal Australian and New Zealand College of Radiologists (RANZCR), Quality Use of Diagnostic Imaging (QUDI), study. Paediatric data were submitted to the NDRLS in 2012 through 2015. An analysis has been made of the NDRLS paediatric data using the same method as was used to analyse the QUDI data to establish the Australian national paediatric DRLs for MDCT. An analysis of the paediatric NDRLS data has also been made using the method used to calculate the Australian national adult DRLs for MDCT. A comparison between the QUDI data and subsequent NDRLS data shows the NDRLS data to be lower on average for the Head and AbdoPelvis protocol and similar for the chest protocol. Using an average of NDRLS data submitted between 2012 and 2015 implications for updated paediatric DRLS are considered.

Objective: To evaluate the diagnostic efficacy of single-pass contrast-enhanced multidetector CT (CE-MDCT) performed with a low-radiation high-contrast (LR-HC) dose protocol in selected patients with non-traumatic acute bowel disease., Methods: 65 (32 males, 33 females; aged 20-67 years) consecutive patients with non-traumatic acute bowel disease underwent single-pass CE-MDCT performed 70-100 s after i.v. bolus injection of a non-ionic iodinated contrast medium (CM) (370 mgI ml -1 ). In 46 (70%) patients with a clinical and/or ultrasonographic suspicion of inflammatory bowel disease, up to 1.2-1.4 l of a 7% polyethylene-glycol solution was orally administered 45-60 mins prior to the CT examination. Patients were then divided into two groups according to age: Group A (20-44 years; n = 34) and Group B (45-70 years; n = 31). Noise index (NI) and CM dose were selected as follows: Group A (NI = 15; 2.5 ml kg -1 ) and Group B (NI = 12.5; 2 ml kg -1 ). All patients of Group A underwent thyroid functional tests at 4-6 weeks. Final diagnoses were obtained by open (n = 12) or laparoscopic surgery (n = 4), endoscopy w/without biopsy (n = 24) and clinical (n = 19) and/or instrumental (ultrasonography) (n = 6) follow-up at 11 ± 4 months (range 6-18 mo.). Statistical analysis was performed by χ 2 and Student's t-test for categorical and continuous variables, respectively., Results: Sensitivity and specificity were 91.3 vs 95.4% (p = 0.905) and 90.9 vs 88.8% (p = 0.998) with an overall diagnostic accuracy of 91.1 vs 93.5% (p = 0.756), whereas the radiation (in millisievert) and CM dose (in millilitre) were 7.5 ± 2.8 mSv and 155 ± 30 ml for Group A and 14.1 ± 5.3 mSv and 130 ± 24 ml for Group B (p < 0.001), respectively. No patients of Group A showed laboratory signs of thyrotoxicosis at follow-up., Conclusion: The LR-HC has proved to be a safe and a dose-effective protocol in the evaluation of selected young patients with non-traumatic acute bowel disease. Advances in knowledge: (1) As reaching the highest diagnostic benefit to risk ratio (AHARA) appears to be the current principle of MDCT imaging, an increased amount of iodinated CM (0.7-0.9 gI ml -1 ) can be safely administered to young patients (<40 years) with normal thyroid and renal function to compensate for the lower image quality resulting from low-dose CT protocols performed with the standard filter back-projection algorithm. Such an approach will result in a significant reduction of the radiation dose, which could be otherwise achieved only using iterative reconstruction algorithms combined with either low tube voltage and/or low tube current protocols. (2) An optimal scan delay (T delay ) for a venous phase caudocranial acquisition can be calculated by the following formula: T delay  = CI + 25 - T SD , where CI is the duration of the contrast injection, 25 is the average of the sum of abdominal aortic and peak hepatic arrival times and T SD is the scan duration. With such an approach, the radiation exposure resulting from bolus tracking, albeit performed with low-dose scans, can be spared in patients with normal transit times.

Rationale and Objectives: Although multiple studies have shown excellent accuracy statistics for noninvasive angiography by coronary computed tomographic angiography (CCTA), most studies comparing nuclear imaging to CCTA were performed on patients already referred for cardiac catheterization, introducing referral and selection bias. This prospective trial evaluated the diagnostic accuracy of 64-row CCTA to detect obstructive coronary stenosis compared to myocardial perfusion imaging (MPI), using quantitative coronary angiography (QCA) as a reference standard., Materials and Methods: Twelve sites prospectively enrolled 230 patients (49% male, 57.8 years) with chest pain. All patients underwent MPI and CCTA (Lightspeed VCT/Visipaque 320, GE Healthcare, Milwaukee, WI, USA) prior to invasive coronary angiography (ICA). All patients were evaluated, and those found to have either an abnormal MPI or CCTA were clinically referred for ICA. CCTAs were graded on a 15-segment American Heart Association model by three blinded readers for presence of obstructive stenosis (>50% or >70%); MPI was graded by two blinded readers using a 17-segment model for estimation of the % myocardium ischemic or with stress defects. ICAs were independently graded for % stenosis by QCA. The efficacies of MPI and CCTA were assessed including all vessel segments for per-patient and per-vessel analyses., Results: The prevalence of stenosis ≥50% by ICA was 52.1% (25 of 48). The sensitivity of CCTA was significantly higher than nuclear imaging (92.0% vs 54.5%, P < 0.001), with similar specificity (87.0% vs 78.3%) when obstructive disease was defined as ≥50%. CCTA provided superior sensitivity (92.6% vs 59.3%, P < 0.001) and similar specificity (88.9% vs 81.5%) using QCA stenosis ≥70%. For ≥50% stenosis, the computed tomographic angiography odds ratio for ICA disease was 51.75 (95% CI = 8.50-314.94, P < 0.001). For summed stress score ≥5%, the odds ratio for ICA CAD was 12.73 (95% CI = 2.43-66.55, P < 0.001). Using receiver operating characteristic curve analysis, CCTA was better at classifying obstructive coronary artery disease when compared to MPI (area = 0.85 vs 0.71, P < 0.0001)., Conclusions: This study represents one of the first prospective multicenter, controlled clinical trials comparing 64-row CCTA to MPI in the same patients, demonstrating superior diagnostic accuracy of CCTA over myocardial perfusion single photon emission computed tomography (MPS) to reliably detect >50% and >70% stenosis in stable chest pain patients., (Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Treatment of pancreatic ductal adenocarcinoma (PDAC) remains a challenge, given its propensity for early systemic spread and growth into the adjacent vital vascular structures. With the advent of newer surgical techniques and chemoradiation therapies, multidetector computed tomography (CT) plays a crucial role in the identification of patients with borderline resectable disease who may benefit from such treatments. Stage III PDAC is divided into two categories-locally advanced, defined by arterial encasement or nonreconstructible portovenous axis involvement; and borderline resectable, defined by limited arterial involvement and/or reconstructible portovenous involvement. A consensus definition for stage III borderline resectable PDAC has been proposed by the Americas Hepato-Pancreato-Biliary Association, the Society of Surgical Oncology, and the Society for Surgery of the Alimentary Tract and has gained widespread use. Evaluation of borderline resectable disease involves the identification of the circumferential and longitudinal relationship of the tumor with its neighboring vessels, markers of vascular invasion, and aberrant anatomic structures that alter the surgical approach. Furthermore, the use of template-based radiology reporting may increase the objectivity of the evaluation and mandate the provision of all of the key descriptors required for a comprehensive evaluation of the disease. In this review, the staging of PDAC at multidetector CT is described, with reference to the evaluation of the tumor-vessel interface as it guides treatment planning, along with a discussion of the key descriptors of PDAC at multidetector CT and their importance. Examples are provided of the imaging findings of borderline resectable disease and different surgical approaches, along with a discussion on the importance of standardized terminology and template-based reporting. © RSNA, 2016.

Purpose: To compare the accuracy of the conventional and portal vein tracing methods in the right hepatic lobe in multidetector computed tomography (MDCT)., Materials and Methods: This retrospective study included patients with hepatocellular carcinoma (HCC) lesions in the right hepatic lobe who underwent multiphasic MDCT and C-arm CT hepatic arteriography (C-arm CTHA) for chemoembolization. The accuracies of the conventional and portal vein tracing methods were evaluated using C-arm CTHA as the gold standard., Results: A total of 147 patients with 205 HCC nodules were included. The C-arm CTHA could identify all the tumour-feeding arteries and consequently demonstrated that 120 lesions were located in the anterior section, 78 in the posterior section, and 7 in the border zone. The accuracy rates of conventional vs. portal vein tracing methods were 71.7 % vs. 98.3 % for the anterior section lesions, 67.9 % vs. 96.2 % for the posterior section, and 28.6 % vs. 57.1 % for the border zone. The portal vein tracing method was more accurate than the conventional method (P<0.001)., Conclusions: The portal vein tracing method should be used for sectional localization of HCCs in the right lobe, because it predicts the location more accurately than the conventional method., Key Points: • Portal tracing method is more accurate than conventional method for tumour localization. • The conventional method is especially inaccurate in right anteroinferior or posterosuperior quadrants. • Scissurae between right anterior and posterior section may not be vertical but tilted.

Objectives: To compare the image quality between fine focal spot size (FFSS) and standard focal spot size (SFSS) in computed tomography of the abdomen and pelvis (CTAP) METHODS: This retrospective review included all consecutive adult patients undergoing contrast-enhanced CTAP between June and September 2014. Two blinded radiologists assessed the margin clarity of the abdominal viscera and the detected lesions using a five-point grading scale. Cohen's kappa test was used to examine the inter-observer reliability between the two reviewers for organ margin clarity. Mann-Whitney U testing was utilised to assess the statistical difference of the organ and lesion margin clarity., Results: 100 consecutive CTAPs were recruited. 52 CTAPs were examined with SFSS of 1.1 × 1.2 mm and 48 CTAPs were examined with FFSS of 0.6 × 0.7 mm. Results showed that there was substantial agreement for organ margin clarity (mean κ = 0.759, p < 0.001) among the reviewers. FFSS produces images with clearer organ margins (U = 76194.0, p < 0.001, r = 0.523) and clearer lesion margins (U = 239, p = 0.052, r = 0.269)., Conclusion: FFSS CTAP improves image quality in terms of better organ and lesion margin clarity. Fine focus CT scanning is a novel technique that may be applied in routine CTAP imaging., Key Points: • Fine focal spot improves organ margin clarity. • Fine focal spot improves lesion margin clarity. • Fine focal spot can be used in routine CT abdominal imaging.

Objective: To compare image quality and diagnostic validity of CBCT and MSCT for distal radius fractures., Methods: 35 CBCT and 33 MSCT scans were retrospectively reviewed with a visual grading scale regarding the depiction of cortical bone, trabecular bone, articular surfaces, and soft tissue. The extent and type of artefacts was analyzed. Agreement on AO classification and measurement of cortical disruption and length of the fracture gap was determined. Fracture reduction was evaluated in post-treatment x-rays. Statistical analysis was performed with visual grading characteristics (VGC), chi square tests, and Kendall's coefficient of concordance., Results: CBCT performed significantly worse for cortical bone, articular surfaces, and especially soft tissue. Trabecular bone showed no significant difference. Significantly more CBCT images showed artefacts. Physics-based artefacts were the most common. CBCT scans also showed motion artefacts. There was no significant difference in agreement on AO classification. The agreement on measurements was substantial for both modalities. Slightly more fractures that had undergone MSCT imaging showed adequate reduction., Conclusion: This initial study of an orthopaedic extremity CBCT scanner showed that the image quality of a CBCT scanner remains inferior for most structures at standard settings. Diagnostic validity of both modalities for distal radius fractures seems similar., Key Points: • Subjectively, CBCT remains inferior to MSCT in depicting most structures. • Similar diagnostic validity for CBCT and MSCT imaging of distal radius fractures. • CBCT is a possible alternative to MSCT in musculoskeletal imaging. • Visual grading characteristics (VGC) analysis proves useful in analyzing visual grading scales.

Purpose: Neither the performance of CT in diagnosing penetrating gastrointestinal injury nor its ability to discriminate patients requiring either observation or surgery has been determined., Materials and Methods: This was a prospective, single-institutional observational study of patients with penetrating injury to the torso who underwent CT. Based on CT signs, reviewers determined the presence of a gastrointestinal injury and the need for surgery or observation. The primary outcome measures were operative findings and clinical follow-up. CT results were compared with the primary outcome measures., Results: Of one hundred and seventy-one patients (72 gunshot wounds, 99 stab wounds; age range, 18-57 years; median age, 28 years) with penetrating torso trauma who underwent CT, 45 % were followed by an operation and 55 % by clinical follow up. Thirty-five patients had a gastrointestinal injury at surgery. The sensitivity, specificity, and accuracy of CT for diagnosing a gastrointestinal injury for all patients were each 91 %, and for predicting the need for surgery, they were 94 %, 93 %, 93 %, respectively. Among the 3 % of patients who failed observation, 1 % had a gastrointestinal injury., Conclusion: CT is a useful technique to diagnose gastrointestinal injury following penetrating torso injury. CT can help discriminate patients requiring observation or surgery., Key Points: • The most sensitive sign is wound tract extending up to gastrointestinal wall. • The most accurate sign is gastrointestinal wall thickening. • Triple-contrast CT is a useful technique to diagnose gastrointestinal injury. • Triple-contrast CT helps to discriminate patients requiring observation and surgery.

Purpose: To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures., Methods: As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT., Results: Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities' specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001)., Conclusion: The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run., Competing Interests: The authors have declared that no competing interests exist.

Australian National Diagnostic Reference Levels for paediatric multi detector computed tomography were established for three protocols, Head, Chest and AbdoPelvis, across two age groups, Baby/Infant 0-4 years and Child 5-14 years by the Australian Radiation Protection and Nuclear Safety Agency in 2012. The establishment of Australian paediatric DRLs is an important step towards lowering patient CT doses on a national scale. While Adult DRLs were calculated with data collected from the web based Australian National Diagnostic Reference Level Service, no paediatric data was submitted in the first year of service operation. Data from an independent Royal Australian and New Zealand College of Radiologists Quality Use of Diagnostic Imaging paediatric optimisation survey was used. The paediatric DRLs were defined for CTDIvol (mGy) and DLP (mGy·cm) values that referenced the 16 cm PMMA phantom for the Head protocol and the 32 cm PMMA phantom for body protocols for both paediatric age groups. The Australian paediatric DRLs for multi detector computed tomography are for the Head, Chest and AbdoPelvis protocols respectively, 470, 60 and 170 mGy·cm for the Baby/Infant age group, and 600, 110 and 390 mGy·cm for the Child age group. A comparison with published international paediatric DRLs for computed tomography reveal the Australian paediatric DRLs to be lower on average. However, the comparison is complicated by misalignment of defined age ranges. It is the intention of ARPANSA to review the paediatric DRLs in conjunction with a review of the adult DRLs, which should occur within 5 years of their publication.

Purpose: To propose a standard measuring protocol for type B aortic dissections so as to improve comparability between studies reporting aortic dimensions., Methods: Fifteen computed tomography (CT) scans of type B aortic dissections were measured with a standard protocol by 2 independent observers using postprocessing software. The following parameters were assessed: true, false, and total lumen diameter; true and false lumen volume; and entry tear size, location, and number. Diameters were measured in a perpendicular plane at 2, 10, and 20 cm from the left subclavian artery and 5 cm from the most distal renal artery. True lumen volume was assessed from the left subclavian artery to the aortic bifurcation, while the false lumen volume was from the start to end up to the aortic bifurcation. Entry tear location was assessed in relation to the left subclavian artery. Intra- and interobserver repeatability and agreement were evaluated using the Bland-Altman method, an a priori set of acceptable differences, and Lin's concordance correlation coefficient (LCCC)., Results: Intra- and interobserver mean differences for aortic diameter and true and false lumen volumes were generally within the limits of agreement and the a priori differences; the LCCC showed excellent agreement. Entry tear location, size, and number were difficult to measure in a repeatable manner, with inconsistent correlation coefficients, especially between the 2 observers., Conclusion: This protocol showed acceptable repeatability for aortic diameter and aortic volume measurements. Assessment of entry tears proved challenging and associated with less favorable results. Additionally, investigators are urged to be more transparent regarding the measurement methodology used in studies describing aortic dimensions., (© The Author(s) 2016.)

We evaluated the performance of a new volume computed tomographic (CT) scanner with regards to image quality and signal homogeneity. Twenty-four subjects were prospectively enrolled. Subjects had prior imaging with rate control. Quantitative analyses performed placing regions of interest in myocardium, blood pool, and aorta. Image quality and diagnostic interpretability were assessed using Likert scales. Median heart rate was 60 and 57 bpm for volume and 64-slice coronary CT angiography (P=.02). Improvement in homogeneity was demonstrated within myocardium (30% improvement), blood pool (73%), and aorta (73%). Improvement in image quality observed at per-patient/per-segment level. Pilot study confirmed improvements in signal homogeneity and diagnostic interpretability, despite imaging at higher heart rates., (Copyright © 2015. Published by Elsevier Inc.)

To study the feasibility of evaluation of collateral channel (CC) classification in patients with coronary chronic total occlusion (CTO) by coronary computed tomography angiography (CTA) with reference to invasive coronary angiography (ICA) validation. We retrospectively included CTO-confirmed patients who underwent both coronary CTA and ICA within 1 month. Collaterals were classified by coronary CTA into three types: CC0, no continuous connection between donor and recipient vessel; CC1, continuous thread-like connection; CC2, continuous, small sidebranch-like connection. With comparison to ICA results, the diagnostic performance of CTA-based CC classification was further assessed. 118 patients with 132 ICA-confirmed CTO lesions were included. Compared to ICA-based evaluation, good overall diagnostic accuracy of CT-based CC classification was observed (78%, 103/132, κ = 0.674, p < 0.001). Coronary CTA was also revealed to be accurate in terms of assessment of collateral tortuosity (76.2%, 77/101) and identification of principal donor vessel (70.3%, 71/101). Impaired diagnostic performance was observed in sub-group of septal collaterals as the accuracy for evaluation of the above parameters was 60.6% (20/33), 72.7% (24/33) and 45.5% (15/33) respectively. Non-invasive evaluation of CC classification by coronary CTA correlates well with ICA findings. In addition, the septal collaterals are much less visible at coronary CTA than epicardial collaterals.

Rationale and Objectives: To compare the repeatability and agreement of a semiautomated liver segmentation method with manual segmentation for assessment of total liver volume on CT (computed tomography)., Materials and Methods: This retrospective, institutional review board-approved study was conducted in 41 subjects who underwent liver CT for preoperative planning. The major pathologies encountered were colorectal cancer metastases, benign liver lesions and hepatocellular carcinoma. This semiautomated segmentation method is based on variational interpolation and 3D minimal path-surface segmentation. Total and subsegmental liver volumes were segmented from contrast-enhanced CT images in venous phase. Two image analysts independently performed semiautomated segmentations and two other image analysts performed manual segmentations. Repeatability and agreement of both methods were evaluated with intraclass correlation coefficients (ICC) and Bland-Altman analysis. Interaction time was recorded for both methods., Results: Bland-Altman analysis revealed an intrareader agreement of -1 ± 27 mL (mean ± 1.96 standard deviation) with ICC of 0.999 (P < .001) for manual segmentation and 12 ± 97 mL with ICC of 0.991 (P < .001) for semiautomated segmentation. Bland-Altman analysis revealed an interreader agreement of -4 ± 22 mL with ICC of 0.999 (P < .001) for manual segmentation and 5 ± 98 mL with ICC of 0.991 (P < .001) for semiautomated segmentation. Intermethod agreement was found to be 3 ± 120 mL with ICC of 0.988 (P < .001). Mean interaction time was 34.3 ± 16.7 minutes for the manual method and 8.0 ± 1.2 minutes for the semiautomated method (P < .001)., Conclusions: A semiautomated segmentation method can substantially shorten interaction time while preserving a high repeatability and agreement with manual segmentation., (Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.)

In the last decade, several studies have emphasised the need to understand and optimise the computed tomography (CT) procedures in order to reduce the radiation dose applied to paediatric patients. To evaluate the influence of the technical parameters on the radiation dose and the image quality, a statistical model has been developed using the design of experiments (DOE) method that has been successfully used in various fields (industry, biology and finance) applied to CT procedures for the abdomen of paediatric patients. A Box-Behnken DOE was used in this study. Three mathematical models (contrast-to-noise ratio, noise and CTDI vol) depending on three factors (tube current, tube voltage and level of iterative reconstruction) were developed and validated. They will serve as a basis for the development of a CT protocol optimisation model., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: To prospectively compare reduced-dose (RD) CT colonography (CTC) with standard-dose (SD) imaging using several reconstruction algorithms., Methods: Following SD supine CTC, 40 patients (mean age, 57.3 years; 17 M/23 F; mean BMI, 27.2) underwent an additional RD supine examination (targeted dose reduction, 70-90%). DLP, CTDI(vol), effective dose, and SSDE were compared. Several reconstruction algorithms were applied to RD series. SD-FBP served as reference standard. Objective image noise, subjective image quality and polyp conspicuity were assessed., Results: Mean CTDI(vol) and effective dose for RD series was 0.89 mGy (median 0.65) and 0.6 mSv (median 0.44), compared with 3.8 mGy (median 3.1) and 2.8 mSv (median 2.3) for SD series, respectively. Mean dose reduction was 78%. Mean image noise was significantly reduced on RD-PICCS (24.3 ± 19HU) and RD-MBIR (19 ± 18HU) compared with RD-FBP (90 ± 33), RD-ASIR (72 ± 27) and SD-FBP (47 ± 14 HU). 2D image quality score was higher with RD-PICCS, RD-MBIR, and SD-FBP (2.7 ± 0.4/2.8 ± 0.4/2.9 ± 0.6) compared with RD-FBP (1.5 ± 0.4) and RD-ASIR (1.8 ± 0.44). A similar trend was seen with 3D image quality scores. Polyp conspicuity scores were similar between SD-FBP/RD-PICCS/RD-MBIR (3.5 ± 0.6/3.2 ± 0.8/3.3 ± 0.6)., Conclusion: Sub-milliSievert CTC performed with iterative reconstruction techniques demonstrate decreased image quality compared to SD, but improved image quality compared to RD images reconstructed with FBP., Key Points: • CT colonography dose can be substantially lowered using advanced iterative reconstruction techniques. • Iterative reconstruction techniques (MBIR/PICCS) reduce image noise and improve image quality. • The PICCS/MBIR-reconstructed, reduced-dose series shows decreased 2D/3D image quality compared to the standard-dose series. • Polyp conspicuity was similar on standard-dose images compared to reduced-dose images reconstructed with MBIR/PICCS.

Introduction: The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database., Materials and Methods: Taiwan's Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed., Results: CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C., Conclusion: CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.

Objectives: To introduce efficient stereological approaches for estimating the volume of a normal or enlarged spleen from MDCT., Methods: All study participants underwent an abdominal MDCT. The first group included 20 consecutive patients with splenomegaly and the second group consisted of 20 subjects with a normal spleen. Splenic volume estimations were performed using the stereological point counting method. Stereological assessments were optimized using the systematic slice sampling procedure. Planimetric measurements based on manual tracing of splenic boundaries on each slice were taken as reference values., Results: Stereological analysis using five to eight systematically sampled slices provided enlarged splenic volume estimations with a mean precision of 4.9 ± 1.0 % in a mean time of 2.3 ± 0.4 min. A similar measurement duration and error was observed for normal splenic volume assessment using four to seven systematically selected slices. These stereological approaches slightly but insignificantly overestimated the volume of a normal and enlarged spleen compared to planimetry (P > 0.05) with a mean difference of -1.3 ± 4.3 % and -2.7 ± 5.2 %, respectively. The two methods were highly correlated (r ≥ 0.96). The variability of repeated stereological estimations was below 3.8 %., Conclusions: The proposed stereological approaches enable the rapid, reproducible, and accurate splenic volume estimation from MDCT data in patients with or without splenomegaly., Key Points: • New efficient stereological approaches are proposed for spleen volumetry from MDCT • These volumetric approaches are applicable in patients with or without splenomegaly • Stereological splenic volume estimations from MDCT are rapid, reproducible, and accurate.